On 5/4/21 11:26 AM, Simon Glass wrote:
Hi Sean,
On Sun, 2 May 2021 at 20:55, Sean Anderson seanga2@gmail.com wrote:
This fixes memory being cleared after releasing it. Instead, clear memory before releasing it. In addition, suppress valgrind warnings about writing to free'd memory.
Signed-off-by: Sean Anderson seanga2@gmail.com
common/dlmalloc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/common/dlmalloc.c b/common/dlmalloc.c index 05c8fd87e7..ea51bdf6a6 100644 --- a/common/dlmalloc.c +++ b/common/dlmalloc.c @@ -592,11 +592,13 @@ void *sbrk(ptrdiff_t increment) ulong new = old + increment;
/*
* if we are giving memory back make sure we clear it out since* we set MORECORE_CLEARS to 1
* if we are allocating memory make sure we clear it out since we set* MORECORE_CLEARS to 1 */
if (increment < 0)memset((void *)new, 0, -increment);
if (increment > 0) {VALGRIND_MAKE_MEM_UNDEFINED(old, increment);memset((void *)old, 0, increment);}Can you explain this a bit more? What is the difference?
As it turns out, this patch is wrong. We need to clear memory when we release it if SYS_MALLOC_CLEAR_ON_INIT is set, since calloc assumes that memory has already been cleared if it gets it from sbrk.
Do you need the cast?
Yes (but this is moot)
common/dlmalloc.c: In function ‘sbrk’: common/dlmalloc.c:600:10: warning: passing argument 1 of ‘memset’ makes pointer from integer without a cast [-Wint-conversion] 600 | memset(old, 0, increment); | ^~~ | | | ulong {aka long unsigned int} In file included from include/common.h:21, from common/dlmalloc.c:1: include/linux/string.h:111:22: note: expected ‘void *’ but argument is of type ‘ulong’ {aka ‘long unsigned int’} 111 | extern void * memset(void *,int,__kernel_size_t); | ^~~~~~
--Sean
if ((new < mem_malloc_start) || (new > mem_malloc_end)) return (void *)MORECORE_FAILURE;-- 2.31.0
Regards, Simon